Super Dark Days: Advice from a Meteorologist

Yesterday was an amazingly dark day.  In fact, according to UW meteorologist Mark Albright, it was the darkest day in Seattle (at the UW) since Dec. 8, 2015.  For the technically oriented among you, we had .61 MegaJoules per meter square yesterday, while on December  8, 2015 there was .57.   Essentially the same.  Typically this time of the year we have 2-3 times that amount.

The Seattle Space Needle PanoCan at noon yesterday says it all (see below).
Dark and dismal.

Why so dark?  We start with our northern latitude and the fact that we are within a month of the winter solstice.  Thus, we are near rock bottom for radiation reaching the top of the atmosphere.

Then we are in the cloudiest/stormiest time of the year.  End of November is our worst.

The visible satellite image and the regional radar at noon yesterday tells the story.  Thick clouds and rain greatly reduce the feeble solar radiation reaching the surface.

How bad was it?  Here are the radiation and weather measurements from the roof of my department in Seattle for the 72 hr ending 5 AM today (Wed.)  The bottom panel is solar radiation.

Almost nothing....I couldn't believe it when I first looked at the plot.    The third panel gives temperature (black line).   THE SUN WAS SO FEEBLE THAT THERE WAS NO DAYTIME WARMING.  In fact, temperature dropped during the day.

OK, the sun situation is really bad now.  What do you do?  

Listen to a meteorologist!

My first advice has nothing to do with weather.  Get out during the middle of the day.  Take a walk, go for a run, ride a bike.  Just get outside during the brightest time of the day...that really helps me.

Second, go to whether there are less clouds...and nearly every day there are places to get a lot more light.     For example, head for rain shadow areas in the lee of mountains..

During the winter storm season when southwesterly flow is prevalent, head towards the Olympic Rain Shadow, northeast of the Olympic Mountains.  Northern Whidbey Island, Sequim, Port Townsend, Victoria or the southern San Juan Island will do.

Here is an example...you see the clearing NE of the Olympics?

After fronts go through and the winds turn more westerly, head east of the Cascade crest over the eastern slopes.  Places like Cle Elum. (see satellite image of such a situation).

But during the winter (November to February) don't do too far down into the Columbia Basin.  Why?  Because it often fills up with low clouds.  Very bad.
As shown below.

Sometimes in mid-winter under high pressure, the lowlands are full of low clouds, sometimes from the Willamette Valley to Bellingham.   But the mountains are in the clear! To get out of it, just go up in elevation...drive up to the passes or climb one of our hills.

Now, 10-20 times a year, we get a Puget Sound convergence zone and there are clouds (and often rain) right over Seattle (see below).  Want to escape the murk?  No problemo.  Just head north or south by 10 miles and you will be in sun!

Finally, head up into the snow in our mountains.   Snow reflects solar radiation and makes it much brighter, WHEN there is no active weather going on.

Pretty bright at Snoqualmie Summit!

There are more "secrets" I can tell you, but the message is clear.  Don't be passive in accepting a dark fate. You can do something about it.  90% of the time you can get to a LOT more light with a short drive.

Do what I do on one of the dark days....take a look at the visible satellite imagery (here), find the nearest bright spots, and make your plans!

He May Like the Dark Side.  You don't have to.

from Cliff Mass Weather and Climate Blog http://ift.tt/2i0Wy7R

Super Dark Days: Advice from a Meteorologist

Yesterday was an amazingly dark day.  In fact, according to UW meteorologist Mark Albright, it was the darkest day in Seattle (at the UW) since Dec. 8, 2015.  For the technically oriented among you, we had .61 MegaJoules per meter square yesterday, while on December  8, 2015 there was .57.   Essentially the same.  Typically this time of the year we have 2-3 times that amount.

The Seattle Space Needle PanoCan at noon yesterday says it all (see below).
Dark and dismal.

Why so dark?  We start with our northern latitude and the fact that we are within a month of the winter solstice.  Thus, we are near rock bottom for radiation reaching the top of the atmosphere.

Then we are in the cloudiest/stormiest time of the year.  End of November is our worst.

The visible satellite image and the regional radar at noon yesterday tells the story.  Thick clouds and rain greatly reduce the feeble solar radiation reaching the surface.

How bad was it?  Here are the radiation and weather measurements from the roof of my department in Seattle for the 72 hr ending 5 AM today (Wed.)  The bottom panel is solar radiation.

Almost nothing....I couldn't believe it when I first looked at the plot.    The third panel gives temperature (black line).   THE SUN WAS SO FEEBLE THAT THERE WAS NO DAYTIME WARMING.  In fact, temperature dropped during the day.

OK, the sun situation is really bad now.  What do you do?  

Listen to a meteorologist!

My first advice has nothing to do with weather.  Get out during the middle of the day.  Take a walk, go for a run, ride a bike.  Just get outside during the brightest time of the day...that really helps me.

Second, go to whether there are less clouds...and nearly every day there are places to get a lot more light.     For example, head for rain shadow areas in the lee of mountains..

During the winter storm season when southwesterly flow is prevalent, head towards the Olympic Rain Shadow, northeast of the Olympic Mountains.  Northern Whidbey Island, Sequim, Port Townsend, Victoria or the southern San Juan Island will do.

Here is an example...you see the clearing NE of the Olympics?

After fronts go through and the winds turn more westerly, head east of the Cascade crest over the eastern slopes.  Places like Cle Elum. (see satellite image of such a situation).

But during the winter (November to February) don't do too far down into the Columbia Basin.  Why?  Because it often fills up with low clouds.  Very bad.
As shown below.

Sometimes in mid-winter under high pressure, the lowlands are full of low clouds, sometimes from the Willamette Valley to Bellingham.   But the mountains are in the clear! To get out of it, just go up in elevation...drive up to the passes or climb one of our hills.

Now, 10-20 times a year, we get a Puget Sound convergence zone and there are clouds (and often rain) right over Seattle (see below).  Want to escape the murk?  No problemo.  Just head north or south by 10 miles and you will be in sun!

Finally, head up into the snow in our mountains.   Snow reflects solar radiation and makes it much brighter, WHEN there is no active weather going on.

Pretty bright at Snoqualmie Summit!

There are more "secrets" I can tell you, but the message is clear.  Don't be passive in accepting a dark fate. You can do something about it.  90% of the time you can get to a LOT more light with a short drive.

Do what I do on one of the dark days....take a look at the visible satellite imagery (here), find the nearest bright spots, and make your plans!

He May Like the Dark Side.  You don't have to.

from Cliff Mass Weather and Climate Blog http://ift.tt/2i0Wy7R

Fronts Are Stronger Aloft Than At the Surface Here in the Northwest

Another strong Pacific front will come through tomorrow across western Washington State.  The temperature change will be wimpy at the surface, with a decline of only a few degrees.

But go aloft, to say 5000-10,000 ft, and major temperatures declines will occur (5-15F).

So why are fronts so wimpy at low levels around here?  The answer is below.

 Here is the forecast map for 10 AM tomorrow at 700 hPa (about 10,000 ft).  There is a trough of lower pressure along the coast (solid line), with a slug of cold air with it.  If you look closely, you will see a wind shift with the front aloft and a substantial change in temperature behind (roughly a drop from -8 to -14C, a decline of 6C or about 11F)

A map of sea level pressure and 925 hPA  (about 2500 ft) temperature at 7 AM, shows the front making landfall and a temperature drop of only a few degrees C (3-4F).

A wimpy front at low levels and a much stronger front aloft, at least in terms of temperature.  

The larger temperature changes with the front aloft are even more clear cut in a time-height cross section, which shows the temperatures (red lines), winds (barbs), and humidity (color shading) for the next few days (time increases to the left, height in pressure, with 850 being 5000 ft).  Look at the red lines (temperature)....much greater undulations aloft tomorrow (1128/12-1129/00) .

Why are the  surface temperatures variations associated with our vaunted Pacific fronts so weak around here?

Because of the influence of the vast Pacific Ocean.  At the latitude of our coast, the sea surface temperature is roughly 11 C (52F), extending for thousands of miles!

A blow up section off of our coast show 11-12C water temperatures due east of the WA Coast (below).  Cold air moves off of Asia and Alaska at all levels, but is rapidly warmed over the lower few thousand feet by the relatively warm ocean.  Over time the temperature contrasts with fronts are weakened at low levels, but remain fairly strong aloft.  Those are the fronts that reached our shores.

Want to see the process from space?  Here is a NASA MODIS satellite image from Saturday over the north Pacific.  You can see cold air streaming off of Asia to Alaska, produce lines of clouds resulting from the instability of cold air over warm water.  This process results in warming of the lower atmosphere.

from Cliff Mass Weather and Climate Blog http://ift.tt/2zJEPgp

Fronts Are Stronger Aloft Than At the Surface Here in the Northwest

Another strong Pacific front will come through tomorrow across western Washington State.  The temperature change will be wimpy at the surface, with a decline of only a few degrees.

But go aloft, to say 5000-10,000 ft, and major temperatures declines will occur (5-15F).

So why are fronts so wimpy at low levels around here?  The answer is below.

 Here is the forecast map for 10 AM tomorrow at 700 hPa (about 10,000 ft).  There is a trough of lower pressure along the coast (solid line), with a slug of cold air with it.  If you look closely, you will see a wind shift with the front aloft and a substantial change in temperature behind (roughly a drop from -8 to -14C, a decline of 6C or about 11F)

A map of sea level pressure and 925 hPA  (about 2500 ft) temperature at 7 AM, shows the front making landfall and a temperature drop of only a few degrees C (3-4F).

A wimpy front at low levels and a much stronger front aloft, at least in terms of temperature.  

The larger temperature changes with the front aloft are even more clear cut in a time-height cross section, which shows the temperatures (red lines), winds (barbs), and humidity (color shading) for the next few days (time increases to the left, height in pressure, with 850 being 5000 ft).  Look at the red lines (temperature)....much greater undulations aloft tomorrow (1128/12-1129/00) .

Why are the  surface temperatures variations associated with our vaunted Pacific fronts so weak around here?

Because of the influence of the vast Pacific Ocean.  At the latitude of our coast, the sea surface temperature is roughly 11 C (52F), extending for thousands of miles!

A blow up section off of our coast show 11-12C water temperatures due east of the WA Coast (below).  Cold air moves off of Asia and Alaska at all levels, but is rapidly warmed over the lower few thousand feet by the relatively warm ocean.  Over time the temperature contrasts with fronts are weakened at low levels, but remain fairly strong aloft.  Those are the fronts that reached our shores.

Want to see the process from space?  Here is a NASA MODIS satellite image from Saturday over the north Pacific.  You can see cold air streaming off of Asia to Alaska, produce lines of clouds resulting from the instability of cold air over warm water.  This process results in warming of the lower atmosphere.

from Cliff Mass Weather and Climate Blog http://ift.tt/2zJEPgp

The Fall So Far

We are now over two months into autumn....what kind of fall has it been? 

Temperature-wise over the West Coast (see below)...nothing unusual.  Slightly cooler than normal over most of Washington and Oregon, grading to warmer than normal over the southernmost portions of California.  Toasty in Arizona.

Precipitation has been a bit more interesting.  Coastal Washington and northwest Oregon has been substantially wetter than normal, as have the western slopes of the Cascades.  This last week, of course has been quite wet.

Slightly drier than normal in southern CA.

All the precipitation has been good for business in terms of filling area reservoirs.   The critical Yakima reservoir system is well above normal (blue is current and red is normal), with the combination of heavy precipitation and warmth causing a huge rise in the reservoir levels the past few days. (Note that the current reservoir storage is what would be normal for middle January).

 So things are looking good for Yakima Valley's agriculture next year.   Lots of hops, grapes, and veggies.  Seattle's reservoirs are in good shape as well.

An important element of the eastern WA water supply is the snowpack, and the latest graphic of the snow-water content of the regional snowpack is generally near normal.   Unusually large values in the sodden Olympic Range.  Importantly, the Sierra Nevada snowpack is excellent.

What about the next week?  One weather system after another...with nothing serious (e.g., big winds or heavy rains).  One-week totals from the NWS GFS model (below) are substantial (5-10 inches) over the Olympics, North Cascades and southern BC, and even northern CA gets wetted down.

And there is some good news for skiers.  

Temperatures have been cooling, and although there will be some brief warm interludes, there will be snow at higher elevations above the mountains (particularly above 4000 ft).  The 72hr total snowfall ending 4 PM Wednesday (below) shows several feet of new snow at elevation.  Snoqualmie will be too warm.  Sorry.

In general, a typical fall for our region.

from Cliff Mass Weather and Climate Blog http://ift.tt/2iQJsuB

The Fall So Far

We are now over two months into autumn....what kind of fall has it been? 

Temperature-wise over the West Coast (see below)...nothing unusual.  Slightly cooler than normal over most of Washington and Oregon, grading to warmer than normal over the southernmost portions of California.  Toasty in Arizona.

Precipitation has been a bit more interesting.  Coastal Washington and northwest Oregon has been substantially wetter than normal, as have the western slopes of the Cascades.  This last week, of course has been quite wet.

Slightly drier than normal in southern CA.

All the precipitation has been good for business in terms of filling area reservoirs.   The critical Yakima reservoir system is well above normal (blue is current and red is normal), with the combination of heavy precipitation and warmth causing a huge rise in the reservoir levels the past few days. (Note that the current reservoir storage is what would be normal for middle January).

 So things are looking good for Yakima Valley's agriculture next year.   Lots of hops, grapes, and veggies.  Seattle's reservoirs are in good shape as well.

An important element of the eastern WA water supply is the snowpack, and the latest graphic of the snow-water content of the regional snowpack is generally near normal.   Unusually large values in the sodden Olympic Range.  Importantly, the Sierra Nevada snowpack is excellent.

What about the next week?  One weather system after another...with nothing serious (e.g., big winds or heavy rains).  One-week totals from the NWS GFS model (below) are substantial (5-10 inches) over the Olympics, North Cascades and southern BC, and even northern CA gets wetted down.

And there is some good news for skiers.  

Temperatures have been cooling, and although there will be some brief warm interludes, there will be snow at higher elevations above the mountains (particularly above 4000 ft).  The 72hr total snowfall ending 4 PM Wednesday (below) shows several feet of new snow at elevation.  Snoqualmie will be too warm.  Sorry.

In general, a typical fall for our region.

from Cliff Mass Weather and Climate Blog http://ift.tt/2iQJsuB